Initialize project and update portal port configuration

Set default portal port to 8081, fix Dart build issue in cart screen, and update setup documentation.

Co-Authored-By: Oz <oz-agent@warp.dev>

README.md

@@ -0,0 +1,81 @@
+# Flutter E-Commerce Portal (Dockerized)
+
+A self-contained Flutter web e-commerce portal served through Docker + Nginx.
+
+## Features
+- Flutter web e-commerce layout:
+  - Product grid (home)
+  - Product detail page
+  - Cart page
+  - Checkout skeleton page
+  - User profile page
+- Authentication via Firebase Authentication:
+  - Email + password
+  - Google login
+  - GitHub login
+- Dockerized build and runtime (no host Flutter SDK required)
+
+## Prerequisites
+- Ubuntu with:
+  - Docker Engine
+  - Docker Compose plugin (`docker compose`)
+
+## Project Structure
+- `lib/screens/` UI pages and auth flow
+- `lib/widgets/` reusable UI widgets
+- `lib/models/` domain models
+- `lib/services/` auth, config, catalog, and cart logic
+- `assets/config/` runtime Firebase config templates
+- `Dockerfile` multi-stage Flutter web build + Nginx runtime
+- `docker-compose.yml` app service orchestration
+- `install_portal.sh` one-command install/run
+- `uninstall_portal.sh` cleanup script
+
+## Configure Authentication Providers
+1. Create a Firebase project.
+2. In Firebase Console > Authentication > Sign-in method, enable:
+   - Email/Password
+   - Google
+   - GitHub
+3. In Firebase Console > Project settings > General, copy web app config values.
+4. Create local env file:
+   ```bash
+   cp .env.example .env
+   ```
+5. Edit `.env` and set:
+   - `FIREBASE_API_KEY`
+   - `FIREBASE_AUTH_DOMAIN`
+   - `FIREBASE_PROJECT_ID`
+   - `FIREBASE_STORAGE_BUCKET`
+   - `FIREBASE_MESSAGING_SENDER_ID`
+   - `FIREBASE_APP_ID`
+   - `FIREBASE_MEASUREMENT_ID` (optional)
+6. For GitHub provider in Firebase, configure GitHub OAuth app callback URL exactly as Firebase instructs.
+
+## Install and Run
+```bash
+chmod +x install_portal.sh uninstall_portal.sh
+./install_portal.sh
+```
+
+The portal will be available at:
+- `http://localhost:8081` (default)
+- or `http://localhost:<PORTAL_PORT>` if you changed `PORTAL_PORT` in `.env`
+
+## Uninstall / Cleanup
+Interactive cleanup:
+```bash
+./uninstall_portal.sh
+```
+
+Non-interactive cleanup:
+```bash
+./uninstall_portal.sh --force
+```
+
+This removes containers, local images, networks, and volumes created by this portal's Compose project.
+
+## Notes on Secrets
+- Keep secrets and keys in `.env` only; do not hard-code in Dart files.
+- `.env` is consumed by Docker Compose and injected into the runtime config file inside the container.
+- For production, use a proper secret manager or CI/CD secret injection.